assume cs:code

data segment
        db 'word', 0
        db 'unix', 0
        db 'wind', 0
        db 'good', 0
data ends

code segment
        start: mov ax, data
               mov ds, ax
               mov bx, 0

               mov cx, 4
            s: mov si, bx
               call captial
               add bx, 5
               loop s

       captial:push cx
               push si


       change: mov cl, [si]
               mov ch, 0
               jcxz ok
               and byte ptr cl, 11011111B
               mov [si], cl
               inc si
               jmp short change

            ok:pop si
               pop cx
               ret

code ends
end start
